Indirect down‐regulation of nuclear NF‐κB levels by cobalamin in the spinal cord and liver of the rat

Abstract

We used electrophoretic mobility shift assays to investigate the effects of cobalamin (Cbl) deficiency on the levels of activated nuclear factor-kappa B (NF-kappaB) in the spinal cords (SCs) and livers of rats made Cbl-deficient (Cbl-D) by total gastrectomy or a Cbl-D diet. We chose the SC and liver because they are severely or scarcely affected, respectively, by Cbl deficiency in terms of histological damage. We found permanently increased NF-kappaB levels (particularly the p50 and p65 subunits) in the SCs and livers of both types of Cbl-D rats, and Western blot analysis demonstrated increased p65 levels. NF-kappaB and p65 protein levels normalized when the totally gastrectomized (TGX) rats were treated with Cbl replacement. As we have previously demonstrated that Cbl deficiency increases tumor necrosis factor (TNF)-alpha and nerve growth factor (NGF) levels in the SC (each of which is a known NF-kappaB activator), we redetermined NF-kappaB levels in the SCs and livers of TGX rats treated with anti-TNF-alpha or anti-NGF antibodies and found that NF-kappaB levels normalized in both tissues after either treatment. These results demonstrate that: (1) Cbl physiologically and indirectly down-regulates NF-kappaB levels in rat SC and liver, and (2) NF-kappaB is an important signaling molecule after Cbl deficiency injury.

Biphasic Modulation of NOS Expression, Protein and Nitrite Products by Hydroxocobalamin Underlies Its Protective Effect in Endotoxemic Shock: Downstream Regulation of COX-2, IL-1β, TNF-α, IL-6, and HMGB1 Expression

“…Since Cbl has been shown to prevent NF- κ B activation in a non-immune challenge model [17], and activation of NF- κ B leads to iNOS induction, we first looked at the effects of the five principally occurring, intracellular Cbls, (CNCbl, HOCbl, GSCbl, and the two mammalian enzyme cofactors for MU and MS, respectively, AdoCbl and MeCbl), on LPS-induced NF- κ B activation in vitro, using a canonical reporter assay. Although the various incoming forms of Cbl are all reduced or dealkylated soon after cell entry, prior to MS/MU cofactor formation [60], the different incoming forms affect both the rate and ratio of formation of the two known active cofactors, AdoCbl/MeCbl [60–62].…”

“…A reasonable hypothesis is that such Cbl/TNF- α /IL-6 regulation may be partly effected via Cbl indirect regulation of the central immune regulatory transcription factor, nuclear factor kappa B (NF- κ B) [8]. Normal physiological levels of Cbl in spinal fluid appear to correlate with NF- κ B quiescence, at least, in a non-inflammatory/non-immune challenge model [17]. Recently, a kinetic study reported that Cob(II)alamin reacts with superoxide at rates approaching superoxide dismutase [18].…”

Cobalamin and normal prions: A new horizon for cobalamin neurotrophism

“…We have previously demonstrated that Cbl-deficiency-induced imbalance in the cytokine and growth factor network activates subsequent cellular events in the CNS as it has been shown that nuclear factor-kB activity in rat SC is down-regulated by Cbl as a result of Cbl-induced down-regulation of the nuclear factor-kB inducers TNF-a and NGF [95]. In this paper we demonstrate that the increase in SC PrP C levels is mediated by Cbl-deficiency-induced increase in SC and PNS TNF-a levels [61,96].…”

Mechanistic Studies on the Reaction between Cob(II)alamin and Peroxynitrite: Evidence for a Dual Role for Cob(II)alamin as a Scavenger of Peroxynitrous Acid and Nitrogen Dioxide

“…Specifically, Cbl regulates the production of the proinflammatory cytokines TNF-a and IL-6, epidermal growth factors and nerve growth factors, and suppresses production of the inducible transcription factor NF-kB. [25] Furthermore Cbl therapy normalizes levels of TNF-a and epidermal growth factors in Cbl deficient patients. [26] Considerable amounts of free (nonprotein-bound) Cbl are also achievable upon Cbl supplementation, [27] and an ABC transporter protein that effluxes free Cbl from cells has been identified.…”